Nutritional research has indicated that the addition of 5,8,11,14,17 - eicosapentaenoic acid (EPA), an omega-3 fatty acid, to the human diet appears to reduce triglyceride levels in the blood. This in turn has the potential of reducing the risk of heart disease and atherosclerosis. EPA is also the precursor of several prostaglandins, which are compounds active in lowering blood pressure and causing constriction of the smooth muscle in the bronchi of the lungs. It has also been suggested that EPA may be effective for preventing thrombosis.
If EPA were incorporated into the human diet on a regular basis, the demand for it would substantially increase. This would in turn create a demand for new sources of EPA. The present commercial sources of EPA are concentrated fish oils. These fish oil concentrates are unattractive because they contain cholesterol and have undesirable tastes and odors. Furthermore, fish oils have the potential for containing high levels of heavy metals and pesticides. Thus, there is a need in the art for more attractive sources of omega-3 fatty acids, such as EPA.
While it is known that fungi such as Saprolegnia parasitica, Phytophthora infestans, and Mortierella (spp.), contain EPA bearing lipids, it has heretofore not been known that lactose can be used as an energy source for the production of EPA by filamentous fungi. The preferred lactose containing substrate for use in the present invention is whey or a whey product. This is because approximately 47% of whey production presently goes to waste, thus making it available at relatively low expense. The majority of whey produced by industry is in the form of "sweet whey", a by-product of cheese making which typically contains about 5 wt. % lactose. Spray-dried sweet whey permeate (SWP) contains approximately 80 wt. % lactose. It is produced by separating the lactose fraction from the high molecular weight proteins of sweet whey and spray drying it. SWP is a good substrate constituent for organisms which utilize lactose since it also contains minerals, proteins, and vitamins.
The present invention fulfills a need in the art for an inexpensive source of EPA that is not faced with the deficiencies associated with concentrated fish oils.